Philipp Heck

Field Museum of Natural History and Chicago Center for Cosmochemistry

Experimental Interstellar Residence Times of Presolar Dust Grains from Meteorites

Presolar dust grains are bona fide stardust minerals. They formed before the birth of our Solar System and a small fraction survived in primitive asteroids and comets. The time span between the formation of presolar grains in evolved stars and their incorporation into early Solar System material is poorly constrained. Knowledge of this time span is essential for a better understanding of the processing of grains in the interstellar medium (ISM) and formation processes of the solar system. During their residence in the interstellar medium, dust grains are bombarded by galactic cosmic-rays (GCR). GCR-induced spallation reactions in the dust produce cosmogenic nuclides whose concentrations can be measured with mass spectrometry. Dating of individual presolar grains was difficult because of their small size, low concentrations of cosmogenic nuclides and uncertainties in recoil loss. Recent improvements in instrument sensitivity and recoil loss modeling make it possible to determine reliable relative ages of presolar interstellar dust grains from meteorites.

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